One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(6,8)(9,10,12,14)(11,13,16,15)(18,20)(21,24)(26,30)(27,33)(28,36)(38,40)(1,2)(3,6)(4,5)(7,8)(9,10)(11,13)(12,14)(15,16)(17,18,22,20)(19,21,23,24)(26,30)(28,36)(31,34)(35,39)(3,7)(6,8)(9,10,12,14)(11,13,16,15)(17,19,22,23)(18,21,20,24)(25,26)(27,34)(28,32)(29,30)(31,33)(35,40)(36,37)(38,39)(1,3)(2,6)(4,7)(5,8)(9,10)(11,15)(12,14)(13,16)(17,20,22,18)(19,21,23,24)(25,27)(26,31)(28,35)(29,33)(30,34)(32,38)(36,39)(37,40)(1,2)(3,8)(4,5)(6,7)(9,11)(10,13)(12,16)(14,15)(17,21)(18,23)(19,20)(22,24)(25,28,29,36)(26,32,30,37)(27,35,33,39)(31,38,34,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.